Okay, we have a few different questions there. Let me try and break that down.
Why do the leaves turn color?
1)There’s losing color because of age, ripening, lowered amino acid production, and temperature fluctuations. Colder temperatures bring out more color.
2) There’s a health problem, often being nutrient related.
Throughout veg and the first 8 weeks of a plant’s life, it should stay relatively healthy. Losing some older leaves to yellowing is fine. When other colors come into play, like red and orange, you have an issue. A wide range of possibilities.
3) Will a plant keep it’s color and expressions even after it’s stressed?
Almost always, yes. If you can get that plant back to a healthy vegetative state, it should return to it’s previous morphology.