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