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