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