I see un-coloring empty trains is now a feature and I plan to check it out tonight. I was thinking about updating the old mods with more features and starting with un-coloring but you've beat me too it. The next addition to make this even better for LTN users would be coloring of the trains upon leaving the LTN Depot based on the items it is being sent to pickup instead of waiting until the train has the times to color it.

That is a pretty good idea. It might take a little while for me to figure out how to implement it, but I'll give it a shot.

Implementing should be really simple by subscribing to LTNs interface.
all you need is get_on_dispatcher_updated_event and read the items from event.deliveries.shipment
Interface manual can be found here: https://forums.factorio.com/viewtopic.php?f=214&t=51072&p=397844#p397844