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