FALL OF THE REPUBLIC
Colors were initially used to identify clone trooper officers by rank, but the Jedi encouraged their clones to show individuality, and special unit markings and color patterns quickly spread through the Grand Army of the Republic. Clone commanders also frequently customized their armor.
Improvements to clone armor and equipment were made throughout the Clone Wars; by its final battles, nearly all clones had switched to improved “Phase II” armor. By then, variant forms of armor were also in use for troopers in specialized roles, from pilots to bomb-disposal teams.