Perhaps just the any quality icon?
https://wiki.factorio.com/images/Any_quality.png
With perhaps an "I" on top of it for the module 1, "II" for module 2 and "III" for module 3?
-- OR --
Quality module 1 actually unlocks the standardizer + Post processing building, and then you can use the icon of that post processing building plus the "uncommon" icon.
Quality Module 2 unlocks the Calibration building and you can use the icon of that building plus the "rare" icon.
Quality Module 3 unlocks the reinforcement building, and epic quality. so you can use those respective icons.
Only the last one is a bit annoying because Epic is a separate research after quality module 3 that also is a prerequisite for the legendary research.
Not sure what to do there...