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