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