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