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