One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,7,6,3,4,8)(9,10,12,16,14,18,13,17)(11,19,21,15,22,23,20,24)(25,26)(27,33,35,39)(28,31)(29,32)(30,34,37,40)(36,38)(1,3,6,2)(4,7,5,8)(9,11,13,20,14,22,12,21)(10,15,16,23,18,24,17,19)(25,27)(26,30,32,37)(28,34)(29,35)(31,33,38,39)(36,40)(1,4,6,5)(2,7,3,8)(9,12,14,13)(10,16,18,17)(11,20,22,21)(15,19,24,23)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.