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