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