Good point. The default colours are quite bright, but they can be modified to be much more muted if you wish in the Appearance preference pane.

Oh, one other trick, you can drag snapshots to a split to view them in the full editor (read-only of course). When Option-dragged, they will be loaded into the split in comparison mode. I find it very useful to have both versions of the text side-by-side like that, especially since you can scroll the other split with keyboard shortcuts without switching to it with Ctrl-Opt-Cmd-Up and Down arrows.