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