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