Paint all the flesh with 3:1 Lahmian Medium : Carroburg Crimson
Dry brush the flesh with Wraithbone
Paint all split skin/joints/holes with Volupus Pink
Use White Scar to highlight skin, mostly on the edge of the head and on around skin splits
Claw & Hooves
Use Abaddon Black to cover all claws
Glaze on a transition 2/3 from the tips of the claws with Khorne Red
Use Evil Sunz Scarlet to do some edge highlighting
Add some more hightlight with Wild Rider Red but cover less than the previous highlight
You can use a final point to highlight corner with Troll Slayer Orange
Carapace
Use 1:1 Leviathan Purple : Shyish Purple on all carapace
Use Druchii Violet to cover all carapace
Use Xereus Purple to highlight plates on carapace. Create lines that goes from the middle of the plate to the next one
Paint over those lines with Genestealer Purple but cover a smaller amount than the previous step
Use Slaanesh Grey to dry brush the carapace
Head
Use Nuln Oil for the interior of the mouth and over the teeths
Use Volupus Pink for the tongue
Highlight teeths with Wraithbone
Use White Scar to make sure eyes are as white as possible
Use Flash Gitz Yellow to paint on the eyes, you can cover a bit more than the eyes to give a glowing effect
Add a point of Troll Slayer Orange in the middle of the eyes
Weapons
Start by painting the interal flesh (tubes connected to the weapons) woth Carroburg Crimson . Highlight the interal flesh with some Kislev Flesh and do some doting on the internal flesh with some Pallid Wych Flesh
Paint the carapace and the claws on the weapon with some Abaddon Black . Add contrast on the carapace with line of Xereus Purple then son thinner lines of Genestealer Purpler . Finish with some dots of Slaanesh Grey
For the actual weapon, base coat it with some Guilliman Flesh , then use Volupus Pink for the split skin. Use Carroburg Crimson on the 3 end of the weap but don't fully cover it. On the far end, use Khorne Red to finish the gradient.
For the eyes, first use some White Scar to make sure both eyes are white. Then add somme Flash Gitz Yellow to paint the eyes, you can cover a bit more than the eyes to add a glowing effet. Finally colors the eyes with Troll Slayer Orange