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)(11,15)(12,16)(13,14)(19,23)(22,24)(25,26,29,32)(27,33,35,30)(28,31,36,38)(34,39,40,37)(1,3,6,5)(2,7,8,4)(9,10,13,14)(11,15,16,12)(18,21)(22,24)(28,36)(31,38)(34,40)(37,39)(3,5)(4,7)(11,16)(12,15)(17,18,20,21)(19,22,23,24)(25,26)(27,33)(28,31)(29,32)(30,35)(34,39)(36,38)(37,40)(1,4,6,7)(2,3,8,5)(9,11)(10,12)(13,16)(14,15)(25,27,29,35)(26,30,32,33)(28,34,36,40)(31,37,38,39)(1,5,6,3)(2,7,8,4)(9,12)(10,11)(13,15)(14,16)(17,19,20,23)(18,22,21,24)(25,28,29,36)(26,31,32,38)(27,34,35,40)(30,37,33,39)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.