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)(19,23,24,21)(25,26,29,30)(27,31,34,38)(28,32,37,36)(33,39,35,40)(9,10,12,14)(11,13,16,15)(19,24)(21,23)(26,30)(31,38)(32,36)(39,40)(9,10)(11,13)(12,14)(15,16)(17,18)(19,21)(20,22)(23,24)(25,27,29,34)(26,31,30,38)(28,35,37,33)(32,40,36,39)(1,2)(3,6)(4,5)(7,8)(9,10)(11,13)(12,14)(15,16)(17,19)(18,21)(20,24)(22,23)(25,26)(27,31)(28,36)(29,30)(32,37)(33,40)(34,38)(35,39) involution — undirected(1,3,4,7)(2,6,5,8)(9,11,12,16)(10,13,14,15)(17,18)(19,21)(20,22)(23,24)(25,28)(26,32)(27,33)(29,37)(30,36)(31,39)(34,35)(38,40)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.