Forgot to make this post, but another process behind Saitama's version:
Alone - A callback to the side chapter 200 yen, and it is the earliest establishment of one of the most constant thing about Saitama - loneliness. He's a kid, weak, avoided attracting attention be it good or bad, and there is absolutely no one on his corner . In contrast to how Genos as a child, colorful and saturated, Saitama's pallor is more grey, it's bland to look at, but the shadows are grim, and we look down on Saitama.
Call/Ignite - We get introduce to color, Saitama looks more alive, more saturated, at the backdrop of royal blue that I color picked from the anime screenshot. Where Genos's fire is around him, to Saitama it's within him - which you could see it in his eyes, the only eyes in the sequence that ends up colored as both the turning point and igniting point of his life when he chooses to do the right thing and live as a hero.
Bored - I think it speaks for itself.
Loss - I can say one thing - it was hard to capture the moment where Genos became a crucial part of Saitama's life because he integrated to it so seamlessly and so subtly, but we and Saitama can all pinpoint the moment where we fully realize just how important Genos to him - exactly the moment he was gone. If most of Saitama's palette are not so colorful, this is the part where all colors leave.
Apotheosis/Nadir - A callback to Alone. In response to Genos's death, Saitama's emotions surged, and so did his strength. In response to his loss, he has transcended to a god. Hence why he shares his palette with God's appearance in chapter 153: Forfeit. He's transcended, he's at the peak of his powers so far - but this is his lowest point. He has failed in every sense - as a hero, as a teacher, as a friend. We didn't see his face in chapter 168, but I speculate it looked something like this.
