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