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