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