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