Normally, whether your map is colormap or greyscale depends on a worldconfig setting: /worldconfig colorAccurateWorldmap true/false

This gives all players on the server the same type of map. Most servers enable colormap because it's simply more popular. However, the colormap isn't very good for players with colorblindness, as it makes it extremely difficult to see waypoints on the map. And it's unfair to the rest of the server for the disability of one player to force everyone else to use an option they don't want to use. This clientside mod forces your map to be greyscale, so even on a server that is set to colorAccurateWorldMap you can still have a greyscale map and still be able to see your waypoints. This would be a great accessibilty feature to add to the base game.