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