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