That looks good for like one of the Csgith egg-sacks. As for color:Filth.
The Csgith are supposed to be a truely revolting and disgusting race, that are considered to be hideious by nearly all cultures.
Of course, the Csgith are not supposed to be evil. They are simply doing what they need to do in order to survive:Reproduce. Of course in order to do this other sentients must die. mwuhahah! lol
For the ships, maybe I'll make a standard pic, something looking like yellow mould, and I will make different Version of it by changing the size and the shape. Think it's useless to design carriers, drone... ?
Oooh. Very Very Nice ^__^. For Population make the images be Egg Sacks, Infantry are Infected Humanoids.
And yeah basically ships should be generic and have mold and goo on them. The ships should be banged up(as the Csgith dont bother repairing captured ships, after all Ships only serve to transport and spread the Csgith)
Maybe have goo leaking forth from the ships reactor coolant perhaps? Remember: Filth.