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