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