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