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