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