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