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