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