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