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