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