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