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