A good friend of mine from grad school is red-green colorblind, as are about 8 to 10 percent of men. One of our professors used colored chalk, which is helpful to some people, but always used red and green, making it difficult for my friend to understand the drawings.
Since then, I have been sensitive to the needs of colorblind people when preparing presentations, and when watching other people's presentations. So, I advise you to avoid using red and green together on a graph or diagram unless necessary. Try red and blue, or blue and green. Thank you.