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