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