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