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