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