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