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