A lot of the North Sunfish race sails had colored luff tabs. Blue and purple were common, but I have never seen yellow.
In recent years, they are all white.
Yellow and orange were also used. Don't believe I have ever seen red or green. The first couple years of racing sails were white edges, then there were a number of years with colored edges, then for at least 12 or 14 years they have been white.