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