The gray shades, as he moves away from the chaotic world signifies a sense of relief and calmness. The shade being motionless and emotionless leaving the sky, does not energize, rejuvenate or excite.
Moreover he leaves behind hot shade of orange giving his last sensation of heat. Also, symbolizing energy, vitality, cheer, excitement, adventure, warmth, and good health to his Earthy people. It also represents enthusiasm that he will come again even with more glory.
Thus, creating an elegant painting on the canvas of sky.