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