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