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