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