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