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