If ANY universal ordering system exists for colors, it’s the rainbow sequence.

When you’re deep in the comments with many color bars, it becomes a bit of an unorganized mess. It’s hard to see whether a particular comment is in the 2nd, 3rd, 4th, etc layer relative to the root comment. Having them ordered by RED, ORANGE, YELLOW, GREEN, etc, makes it INSTANTLY clear which layer the current comment is in.

After Purple, (you may add magenta), you just start over with RED.