For a creature to be affected by Color Spray, their hit points must be equal to or less than the remaining total of points accumulated from the Color Spray dice rolls. However, if the creature's hit points are equal to or less than the remaining total, that creature would be immediately killed.
Color Spray's description states, in part (emphasis mine):
Starting with the creature that has the lowest current hit points, each creature affected by this spell is blinded until the end of your next turn. Subtract each creature's hit points from the total before moving on to the creature with the next lowest hit points. A creature's hit points must be equal to or less than the remaining total for that creature to be affected.
Therefore, there would be no purpose to the creature being blinded "until the end of your next turn" because the creature would be dead.
Am I missing something here? It seems like it's impossible for a creature to be dead AND blinded simultaneously because their death would take precedence. So, what's the point of the blinding effect if every creature that would have been blinded is killed first?