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