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