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