You can change the colors that are shown on the purchase order. Colors are saved by individual Users.

Load a current Purchase Order or Receiving. Click on 'Models' from the Toolbar.
Located at the bottom of this screen is the Color Legend.

With your mouse click on the type (i.e. OPEN, RECEIVED, etc) to set the color you want.
Once you have clicked on the type you will see this screen.

Click on the Color you would like and the click 'OK'.
The color you select is now set for the user that is currently logged in.