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