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