I have no ruleset for now. Only a scratch test file.
I use the sectoid with glass cause it has 2 color to play with.
(I may have used a regular floater, but I have the sectoid at hand).
Just comment spriteFaceGroup, spriteFaceColor, spriteHairGroup, spriteHairColor and you have the original sprite (with glass).
The rule apply to all sectoids (armor is the same for all).
If you want colored ranked alien, you must give a different armor to each rank, but the sprite could remain the same.
TODO: how things change when the colors from the 2 arrays have different values.
For the mod: I will do it, but need more time
Oh, and for the good job: Thank but all the credit is for Yankes!