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