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