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