Messy network cables?

Not for ethernet. The only standards I’ve seen that are still deployed are for fiber jumpers, where multimode is orange and single mode is yellow. There are different ends for fiber optic jumpers as well, they are also color coded.

Experience here goes along the lines of that I’ve always only color coded ethernet based on cable type. CAT5, CAT5E, and CAT6, stranded and un-stranded all have different color sheathing. Even so, this isn’t a standard and is just what we’ve done in one place to keep a grasp on what’s what.

Ethernet cables come in all sorts of colors and are not limited to a specific CAT. I have never heard of official color standards for purposes, but I always standardize a color if multiple connection types are present. I usually use blue for voice, black for data, red or orange for a fiber uplink, etc. Just choose something that works for you.
Many companies sell special devices to help you manage your cables. What type of setup are you talking about? Is it a network closet with 4 post racks? Or are we talking about a table in a room covered in cables and servers?

It’s all about how you want to do it. You choose. FREEDOM OF CHOICE!

For ethernet, not really, although most distributors of wire and cables will have different assortments of colors so you don’t get confused as to which wire is what.