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