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