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