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