How do I change the color of my Caliburn?

[Mist of Majora]

They just added this feature today, but I can't figure out how to do it with my Murkmobile. Maybe I need to buy the other one?

[Crimsomrider]

I tried it with a bought Caliburn and it shows an icon in the bottom left to customize the vehicle's colors (for me the keybind was Y).