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