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