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