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