Here is the list of some samples of cover letter for Scholarship Applications. It would be helpful to have a look at these and make any adjustment to your own application. Good luck !!!
University of Louisville: scholarship cover letter sample
University of New South Wales (Australia): Vacation Scholarship cover letter sample (Environmental)
Columbia University: Do's and Dont's's in cover letter with samples (English, Music, Biology, Engineering, Classics samples)
University of Michigan Flint: Writing cover letter for scholarship instruction with samples
The Pennsylvania State University: resume and cover letter tips