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