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