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