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