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