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