My all time favourite graduation book is "Oh the Places You'll Go", by Dr. Seuss, my cousin gave me a copy of this many years ago and I've cherished it since.
This book would be a great source of inspiration.
I love the idea of making your own graduation hat and decorating. Use card- a long strip and a square.
Name based art is also lovely
http://happyhooligans.ca/name-art-sharpies-tin-foil/?utm_source=MadMimi&utm_medium=email&utm_content=Name+Art+with+Sharpies+and+Tin+Foil+_+A+Cool+Art+Project+for+Kids&utm_campaign=20160107_m129174077_RSS+Feed+for+http://happyhooligans_ca/feed&utm_term=Name+Art+with+Sharpies+and+Tin+Foil+_E2_80_93+A+Cool+Art+Project+for+Kids
http://artiswhatiteach.blogspot.ie/search?updated-max=2010-12-09T16:39:00-08:00&max-results=7
http://www.artsonia.com/museum/art.asp?id=17674646&exhibit=497990&gallery=y
Memories can be documented through art- how about a word cloud?
https://www.pinterest.com/pin/398005685788683507/
Self portraits are another way to celebrate the children and all they brought to the school!
http://www.mrsbrownart.com/4th.htm
http://ideas.tpet.co.uk/word-portrait/