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