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)(11,14)(12,16)(13,15)(17,18)(19,23)(20,21)(22,24)(25,26,30,28)(27,31,33,34)(29,36,37,32)(35,40,39,38)(9,11,13,12)(10,14,15,16)(17,19,21,24)(18,22,20,23)(27,33)(31,34)(35,39)(38,40)(2,6)(3,8)(10,15)(14,16)(17,20,21,18)(19,22,24,23)(25,27,30,33)(26,31,28,34)(29,35,37,39)(32,38,36,40)(1,3)(2,7)(4,6)(5,8)(9,10)(11,14)(12,16)(13,15)(25,28,30,26)(27,34,33,31)(29,36,37,32)(35,40,39,38)(1,4,5,7)(2,3,6,8)(9,12,13,11)(10,16,15,14)(17,19)(18,23)(20,22)(21,24)(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.