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