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