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