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