This has been a great suggestion. Everyone I've mentioned it to says it's a terrific idea.
We leave the color-coded docklines on the dock: the spliced loops go on the boat and the bitter ends are cleated on the dock, once the correct length is determined. They stay there for the season.
Our normal approach to the dock is to back down at an angle to the dock, using the dock wheel as a fender. Draped on the dock wheel is the blue spring line, ready to be picked up with a boat hook and looped over the midship cleat. This is the important line, as we are backing into the (normally) leeward side of the dock in shallow water with the keel and rudder retracted.
We then pick up the bow lines, hooking at least one of them to the appropriate bow cleat. (Red-port, green-starboard). As the boat backs down against the dock, the bow lines(s) allow the boat to settle in parallel to the dock. Then we secure the white stern lines (not shown).
The important part is attending to the spring and at least one of the bow lines. By using the color coding, we can instruct unfamiliar crew with what goes where.
It helps to get it right the first time, as boat is not very maneuverable with the “landing gear” retracted and the muddy bottom comes up within a boat length from the docked position. If you don’t spring the boat promptly, the rudder will dig into the mud at low tide and keep the boat from swinging against the dock.