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