Hi Dubbya, I'm the sculptor of the figures, so have re-read the books, and graphic novels (those are in b&w).
I might be misremembering though, so hopefully an expert chimes in. It's pretty vague in the books overall!
The Pig Order have Red armour, Mantis Order have Jade armour, Bull Order have Purple armour, Wolf Order have Black armour.
The goodguys / Kamarg are mentioned with light blue cloth or flags at least once. And the Leader Count Brass, has brass armour.
This could look incredibly OLDHAMMER if done as full colour, so I personally might make all the Granbretan armor black, with just coloured clothing / accessories.
The Kamarg could be in various brass/gold/silver tones, with light blue, light green, white cloth? Would give a nice contrast I think.