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