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