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