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