One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,5,7,6,3,4,8)(9,10,12,17,14,18,13,16)(11,19,21,15,20,24,22,23)(25,26)(27,33,35,39)(28,31)(29,32)(30,34,37,40)(36,38)(1,3,6,2)(4,7,5,8)(9,11,13,22,14,20,12,21)(10,15,17,24,18,23,16,19)(25,27)(26,30,32,37)(28,34)(29,35)(31,33,38,39)(36,40)(2,3)(7,8)(11,20)(15,23)(19,24)(21,22) involution — undirectedA 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.