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)(18,20)(19,23)(25,26)(27,30)(28,33)(29,34)(31,36)(32,38)(35,39)(37,40)(3,8)(5,7)(19,23)(22,24)(26,27)(31,33)(32,34)(39,40) involution — undirected(1,3)(2,5)(4,8)(6,7)(9,10,13,12)(11,14,15,16)(17,18,21,20)(19,22,23,24)(25,27,30,26)(28,33,36,31)(29,32,38,34)(35,39,37,40)(1,3)(2,5)(4,8)(6,7)(9,11,13,15)(10,14,12,16)(17,19,21,23)(18,22,20,24)(25,28)(26,31)(27,33)(29,37)(30,36)(32,40)(34,39)(35,38)(1,2)(3,5)(4,6)(7,8)(9,12,13,10)(11,16,15,14)(17,20,21,18)(19,24,23,22)(25,29,30,38)(26,32,27,34)(28,35,36,37)(31,39,33,40)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.