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