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