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