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