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