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