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