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