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