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