Here is what I use to build a color scheme... Example the commando Body type has to be used for three Diffrent Factions.
The body base is a T-shirt, Cargo pants and Boots. All other parts are added ontop of this by attachment handles in the model itself.
The fact is if ever uniform was colored the same no one could tell which side any one was on. Thankfully there are many type of BDU based on the same Cutting pattern. thus the Shape can be teh same but the uniform will look dramaticly diffrent.
Heres the Example of two Diffrent Factions Base Colors. Please not the image is not what I'm using to build the model with, just an idea of what colors goes where.
First we have STUD's BDU colorations:

This is a custom Uniform made for STUD which no other brance or privet buy can get. thus making them distictive. Notice they don't much care about Camo patters like the Army or DEEP-6. this isbecasue the Zombie have such a blurry eye sight it doesn't much matter, hiding the human figure with color splotchs.
Now we have The Army's ACU colored Patterns.

These are the Flattened out Colors of the Army Digital Pattern Known as ACU there are 3 colors used in ACU and it all pixelated. if you download this image and zoom it in by alot. you'll find that the Colors are indeed Pixelated much the same as the Army's ACU pattern. This will be of much higher detail when I crate the Tinting Texture to go oce the Cloth texture base.
When i build a model i can have the parts look any way i wish and the two diffrent faction will all look diffrent. even thought he base Body model is all exatly the same.