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