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