There is an app called CVSimulator which will filter your pictures to show various kinds of color-blindness. If you select 'P' for protanopia you get an approximation of how dogs see colors.
Here are the colors I recently chose for decorating my apartment:
And here is how they might look to the dogs:
So, basically I choose to focus on the two colors, red and green, that humans and dogs see completely differently. Oops.
For more about color vision in dogs visit my Dogster.com post "In Case You Were Wondering: Here's How Colors Look to "Color-Blind" Dogs"