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