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