He deffo needs the full Baron Samedi face paint. Its a lovely fig too, very characterful.
Personally, I'd do the snake in bright colours like you suggest, if only so it would stand out against his skin (as that would be african if I did it).
Then I'd do the big snake in a luminous, ghostly green to look like a projection or manifestation, something I'm sure I remember seeing in a Doc Savage movie (starring TV Tarzan Ron Ely?).