I guess it would depend on how it died. If it died of some sort of poisoning (like if you fed your dog chocolate or something) then I would think it'd look about the same. But if it got hit by a car, obviously a few things would be off.
'This item will resurrect your dead Creatu from the pits of Reiflem's graveyard. WARNING: All Creatu are currently resurrected in their species' basic color scheme....'
Yeah, long ago the pets turned natural when resurrected, but that was changed way back in V1. I guess the staff just forgot to update the potion's deion, which is understandable, considering that even that time when this colour-changing thing was changed, the pets could not die (still cannot I think) and also blessed flowers were impossible to find. So actually no-one really owned or used a resurrection potion, so no-one noticed. I do not know for sure of course, as I never had a dead pet.