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