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