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