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