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