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