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