First of all this is an amazing mod and will be in all my modded saves from now on. When I last played Factorio (just before the 2.0 release) I had resigned myself to the fact this game would never have character skin mods. I started up a new save a few weeks ago and looked a the characters mod tab on a whim, thinking that it would just be tweaks, armor, hand weapons, and the like. To my surprise I saw a handful of skin mods one of them being a kabold skin which I planed on using when, low and behold, on the last page was this gem of a mod. I'm a big fan of dragons, so when I saw this mod and how well it was done it was an instant favorite. Thank you for this awesome mod. Now for my suggestion.
SUGGESTION: Would it be possible to add (as an option) the ability for the wing membrane to be player colored? Either the same saturation as the armor or a little bit lighter (or both as options)? The reason I ask is that unlike the base character, were you can clearly see your color no mater what; direction your facing, camera zoom level your at, or armor your wearing, you don't see much of your player color on the dragon unless your facing in the south directions (SW, S, SE). You can see the wings from all directions hence why suggested them. Another option would be to have the dark red/brown parts pull from the player color and leave the wing membranes as is. In fact you could add them both as options as a drop down in the settings like:Color - default, wings (mainly the wing membranes and the chest), body (which would include the dark bits on the wings also). If don't want to or cant that's fine, but I hope it's something you might consider.

Thanks for the compliments!

Hrm
TL;DR;
That's a big maybe for the wing membranes (especially if optional), And a big no for the body scales (although it'd be cool)

As much as I like the suggestion, there are a few technical issues

The way the sprites are generated and imported are mostly explained in the Friday Facts #146 and #218
Those give a base idea of the workflow.

To get a bigger picture, you could look at the game data files (IE. Factorio/data/base/graphics/entity/character/level1_idle.png)
In the image file, you can see the parts with custom player colors are grayscaled
Then the way the game stamps custom colors on top is via a mask (IE. level1_idle_mask.png, in the same folder)

Now, the (sane) way masks are generated is per-mesh ("per 3D object")
This would make masking the main body scales nightmarish (I'd have to split the model between body scale vs the rest of the body)
Separating the membranes to make a mask should be okay though

But then we get another issue. If we decide between coloring the armor or the wings, I'd have to provide a few sets of sprites.
One where the wings are base color (such as now) and one where they're grayscale
One where the armor is base color and one where it's grayscale (such as now)
And this is on top of adding new masks sprites
It'd be for all the animations, which is like 12 for each armor state if I recall

And then some other details, I'd have to work on separating the wings, make a version where the armor is colored and where the membranes are grayscaled, I'd have to re-render everything (which would basically take half a day by itself) and then implement the extra sprites in-game and test I didn't mess any of the animations up

And this is without taking the extra download size into consideration
And maybe other issues I haven't considered
but those two are also details

Soooo, big maybe for the wings?

Fair enough. I did know about the mask layer, I just couldn't find a way to get what I was saying across easily (I suck at getting my thoughts down). Also I meant the wings in addition to the armor, just a little lighter color wise than the armor. That way there is more of the player color shown and you don't have to mess with the armors color mask. If that's any easier. The scales were an after thought, so if just the wings happen I'd be happy. Even if you don't this mod is still awesome and I will pretty much always use it.