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