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