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