I generally agree with with @Deus about having a color palette which errs on the muter side most of the time. Not only does it reinforce the feeling of starting off in a barren world which gets gradually colored in by life itself, but it‘s also what‘s been established in most of the concept art of this beginning period of 3D life. If the world had overly colorful terrain and overly fantastical rock formations line eg in No Mans Sky, emerging life couldn‘t be the visual focal point that it should.
Of course, under certain circumstances organisms should be allowed to become as colorful as they sometimes are on earth, but only when it‘s for a good reason such as mate or pollinator attraction, poison signaling or other similar reasons.