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