Since many of the shared macros here use the same convention, ie
I'd say it'd be very useful if KM used a set of default colors when creating an action, that way it's 10x times easier to distinguish what an action is for, and also a time-saving feature for every user.
While I tend to agree, tastes and styles vary so much that I'd expect it would be hard to obtain a consensus.
So, what I do is use this great macro system: MACRO: [KMFAM] Favorite Actions and Macros by @DanThomas.
This enables you to fully customize any Action and then save it to your personal library of Actions. These are just as easy (maybe easier) to find and insert into your Macro as the normal KM "Insert Action by Name" menu.
I use Dan's system many times a day, and have been since he released it several years ago.