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