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