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