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