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