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