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