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