Either one is acceptable. The word "role" implies that the participation is active; the person is involved in the activity. The word "part" implies that the participation may be more passive; the person is merely present at the activity. The implications are not especially strong, though; the words are very nearly synonymous. Either choice would be grammatically correct and natural. However, if the sentence is (as it seems here) for the purpose of a curriculum vitae, the purpose would be better served to use the word "role." The writer would want to imply that Cindy's participation is active.