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