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)(11,18)(12,16)(13,21)(14,17)(15,20)(19,24)(22,23)(25,26,30,33,31,28,29,38)(27,32,34,40,36,37,35,39)(1,3)(2,5)(4,8)(6,7)(11,19)(15,23)(18,24)(20,22)(25,27,30,34,31,36,29,35)(26,32,33,40,28,37,38,39)(3,8)(5,7)(9,11,14,19)(10,15,17,23)(12,20,13,22)(16,24,21,18)(25,28,31,26)(27,32,36,37)(29,33,30,38)(34,40,35,39)(2,6)(5,7)(9,12,14,13)(10,16,17,21)(11,20,19,22)(15,24,23,18)(25,29,31,30)(26,33,28,38)(27,34,36,35)(32,39,37,40)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.