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