Paint can be used to create stains, fake dust, or artificial damage. Acrylic or latex paint is best.
Angelus is a paint brand that works especially well with leather and won’t crack like regular acrylic paint. You may want to have some Angelus paint duller on hand to ensure a matte finish (they only offer matte in black and white). Click here for their full color chart.
Spray paints can be risky on faux leather. Most spray paints contain solvents that will not dry on some types of vinyl. Always try to use a vinyl spray paint on vinyl.
If you are working with lighter colors, you can try applying aniline dyes, or even Rit dyes with a sponge or brush.