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