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