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)(28,32)(29,31)(30,35)(33,37)(36,38)(39,40) involution — undirected(2,5)(6,8)(9,10)(11,14)(12,13)(15,16)(17,19,20,23)(18,21,22,24)(25,27)(26,30)(28,35)(29,36)(31,39)(32,34)(33,38)(37,40)(1,3,4,7)(2,6,5,8)(10,13)(14,16)(26,31)(27,35)(29,37)(30,38)(32,33)(34,39)(9,11,12,15)(10,14,13,16)(18,22)(21,24)(27,35)(30,34)(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.