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