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