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