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