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