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