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