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