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