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