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