Dahshat does not have its own, distinct color scheme. Each unit uses whatever scheme it already has from its home faction. This allows you a lot of freedom in what you'd like to paint - you can go with the studio schemes and get a rag-tag, mercenary feel from your army. Alternatively you can go for a unified color scheme for a more professional look. Or anywhere in between - painting all the LI one color and the HI another might turn out pretty great. Ultimately it is completely up to you - that's one of the many beauties of fielding an NA2 army.
For my Ikari I'm actively trying to make every figure different. For Dahshat I have a theme going of White Tigers of the West. So Grey-White and Mostly old Yu Jing figs.
I'm tempted to do green with white trim. Dashat troops are often Muslim (even the Yu Jing units) and green was Mohammed's favourite colour (according to the internet). No way i'm doing Arabic freehand. I mean I would love to but i'm not that good a painter!
I plan to do mine like the Faction logo, armor in the Smokey Grey/Brown. Orange/Tan details. But Helmets will try to remain in the original faction scheme Zuyong/YJ helmets will be its orange, Haaq's their green, Ariadna is up in the air maybe navy or beige). McMurrough's tartan will be orange and tan. I picture it like an All-star football team; the jersey is the same but the helmet is of their team. The uniform unites them but the helmet give them individuality.
According to the mercenary book from the rpg (it was recently released to backers as a beta release) Dashat wears red and tan military uniforms designed to make them look impressive. Dashat gets a full spread.