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