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