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