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