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