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