The complex plane is colored using a spectrum of colors to denote the
argument of a point, and shading to denote the modulus. The origin is
black, infinity is white, and positive numbers are red. The colors
cycle through red, yellow, green, cyan, blue and magenta. Computers
use mixtures of red, green and blue (RGB) on their screens, printers
use mixtures of cyan, magenta and yellow (CMYK).
Technical nonsense:
Our printer doesn't do the conversion (RGB->CMYK) very well (the conversion
isn't linear) so printed pictures will differ from the ones you
see on the screen.