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