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)(11,25)(12,32)(13,19)(14,20)(15,23)(16,22)(17,24)(18,29)(21,33)(26,34)(27,35)(28,38)(30,37)(31,36)(39,40)(1,3)(2,5)(4,7)(6,8)(9,11,15,29,17,31,16,30)(10,18,22,25,24,37,23,36)(12,27,13,26,14,28,33,40)(19,38,32,34,21,35,20,39)(9,12,16,33,17,14,15,13)(10,19,23,20,24,21,22,32)(11,26,29,28,31,40,30,27)(18,34,25,35,37,39,36,38)(3,7)(5,8)(9,13,15,14,17,33,16,12)(10,20,22,19,24,32,23,21)(11,27,30,40,31,28,29,26)(18,35,36,34,37,38,25,39)(9,14,15,33,17,12,16,13)(10,21,22,20,24,19,23,32)(11,28,29,40,31,27,30,26)(18,35,25,39,37,38,36,34)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.