Prime white, liberally apply Gryphonne Sepia to skin areas
armor plates are Knarloc Green, Badab Black wash, hard edge highlighted with more Knarloc Green
Claws/talons/hooves are Charadon Granite with a Badab Black wash, highlighted with Charadon Granite if they're large enough to warrant it
Teeth are picked out in white
Tongues are Hormagaunt Purple
Fleshy sac bits are Hormagaunt Purple, Badab Black Wash, Highlighted with Hormagaunt Purple
As for what I have unpainted...
1 Forgeworld Malanthrope
1 Hive Tyrant
5 Carnifexes
1 Trygon
2 Tervigons
3 Tyrant Guard
6 Hive Guard
4 Zoanthropes
4 Lictors
6 Warriors
1 Broodlord
100(ish) Genestealers
82 Termagants/Devilgaunts
40 Hormagaunts
12(ish) Ripper Swarms