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