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