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