Wax dyes
Here you will find dyes to easily color your wax.
The more coloring you add, the stronger the color.
Which color is ultimately achieved depends very much on which wax has to be colored and whether that wax already has a color and how thick the wax is applied.
For example, a dip wax must be colored more intensely to give the thin shell of wax the same color intensity as a throughly colored cast wax.