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