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