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