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