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