Silver, light blue: President of National Honor Society
Red: Members of National Honor Society
Green: Members of Latin Honor Society
Purple: Members of Math Honor Society
Yellow: Members of Music Honor Society
Yellow and Black: Members of World Languages Honor Society
Light pink: Members of French National Honor Society
Grey and Yellow: Members of Science National Honor Society
White: Members of Spanish National Honor Society
Black: Cum Laude, Magna Cum Laude, Sum Laude (Honors)
Note that these are just some of the most common sash colors and their meanings, and different schools may have different traditions and color assignments.