I'm color blind so color coding does not work for me. But it is simple, like Jeepman said, be aware of what you are doing. Look at the ammo and the gun. Make sure they match. If you are not capable of doing that you are a good candidate for Gene Pool removal. I mean at a glance I can tell the difference between a 30-06 and a 25-06. And between a .308 and .243. Been shooting over 50 years and never made that mistake.
Since I own a .38S&W, 5, .38 Spl, and 7, .357s, I have the potential for a disaster. I'm aware of it and make sure I don't do anything stupid. I also own 2, .45LCs, 1, .454 casull, and 1, .460 S&W. The .460s will fit in the .45s, I've checked. Good way to lose a life. Be aware.