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