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