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