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