Thanks for the welcome.
I matched the g500s to the HHKB with paint, Krylon Colormaster. I tested several types of paint over a few months on the G500s's easy-to-remove back cover, which also serves as the left and right click. Krylon Colormaster paints, particularly gloss finishes, proved to be incredibly wear resistant. Other brands from model manufacturers were much less durable. I let all paints set for ~3 days before using the mouse during paint testing.
Once I had a durable paint, it was just a matter of grabbing colours, disassembling and cleaning the mouse, then painting the components. I set the "sniper" thumb button to LCTRL to ease CTRL+ access, so it was painted gloss red (452108) to match the HHKB control, all of the other buttons are gloss grey (451606), and the body is satin white (453564), product codes are shown in brackets. I would change the body to gloss white if I were to do it again, mostly for improved durability, the satin developed minor shine where my thumb rests after ~1.5 months.
