Apple - How do I change the OS X Mouse Pointer's color?

Anything that allows you to change the color is paid software. Here's MightyMouse.
Unfortunately, it looks like MightyMouse has been discontinued :(

I would recommend this free software that displays a circle around your cursor. When you haven't moved your mouse for awhile and you move it, it'll display a circle around the pointer. Here's the software.

I think this application may help you:

Mouseposé