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