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