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)(25,26)(27,35)(28,31)(29,30)(32,34)(33,38)(36,39)(37,40)(9,11)(10,15)(12,14)(13,20)(16,18)(17,24)(19,22)(21,23)(25,27,31,38,32,39,30,37)(26,33,29,35,34,40,28,36)(1,3,4,8)(2,5,6,7)(9,12,14,11)(10,16,18,15)(13,20,22,19)(17,24,21,23)(25,28,32,29)(26,30,34,31)(27,36,39,35)(33,37,40,38)(11,12)(15,16)(19,20)(23,24)(25,29,32,28)(26,30,34,31)(27,33,39,40)(35,38,36,37)(9,13,14,22)(10,17,18,21)(11,19,12,20)(15,23,16,24)(25,30,32,31)(26,29,34,28)(27,37,39,38)(33,35,40,36)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.