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