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