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