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