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