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