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