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