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