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