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