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