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