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