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