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