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