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