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