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