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