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)(11,15)(12,13)(14,16)(19,23)(21,24)(25,26,30,31)(27,29,33,39)(28,35,38,32)(34,40,36,37)(1,2,4,5)(3,7,8,6)(9,11)(10,14)(12,15)(13,16)(26,31)(29,39)(32,35)(37,40)(2,5)(6,7)(9,11,13,16)(10,15,12,14)(17,18,20,22)(19,21,23,24)(25,27,30,33)(26,29,31,39)(28,36,38,34)(32,40,35,37)(1,2)(3,6)(4,5)(7,8)(9,11)(10,15)(12,14)(13,16)(17,19,20,23)(18,21,22,24)(25,28,30,38)(26,32,31,35)(27,34,33,36)(29,37,39,40)(1,3,4,8)(2,6,5,7)(9,12,13,10)(11,14,16,15)(25,29)(26,33)(27,31)(28,37)(30,39)(32,36)(34,35)(38,40)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.