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