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