If you are reluctant to run to the store for colored paper, and you desperately need a sheet of some color, print it out on a printer. Below are templates for A4 sheets, painted with the main colors that you may need.
Colored A4 sheets for printing
Green |
Lilac |
Blue |
Grey |
Pink |
Orange |
Red |
Brown |
Blue |
Yellow |
Violet |
Black |
Burgundy |
Beige |