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