On a PC, unzip the bootanimation. Use a photo editor of your choice, Photoshop, GIMP, or even MS Paint. Edit the color the circles of all the images how you'd like. Then use a program like 7zip to compress it back into a .zip file. Make sure when you're compressing it, you set the compression level from "Normal" to "Store" or the bootanimation won't work. It's actually pretty simple, just time consuming is all.