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