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