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)(25,26,28,32,29,33,37,30)(27,34,35,38,36,31,39,40)(1,3,5,4)(2,6,8,7)(9,11)(10,14)(12,19)(13,18)(15,23)(16,22)(17,20)(21,24)(26,30)(27,35)(28,37)(32,33)(36,39)(38,40)(1,3,5,4)(2,7,8,6)(9,12,13,20)(10,15,16,24)(11,17,18,19)(14,21,22,23)(1,3,5,4)(2,6,8,7)(12,20)(15,24)(17,19)(21,23)(25,27,28,35,29,36,37,39)(26,31,32,40,33,34,30,38)(1,4,5,3)(2,7,8,6)(10,16)(11,18)(15,24)(17,19)(27,36)(31,34)(35,39)(38,40)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.