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