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