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