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