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)(11,13)(12,19)(14,18)(15,22)(16,20)(17,23)(21,24)(25,26)(27,33)(28,31)(29,32)(30,35)(34,38)(36,40)(37,39) involution — undirected(2,5)(6,7)(9,11,13,10)(12,15,21,17)(14,18,20,16)(19,23,24,22)(25,27,29,36,28,35,37,34)(26,30,32,38,31,33,39,40)(9,12,20,23,13,21,14,22)(10,15,18,24,11,17,16,19)(26,31)(27,34)(29,37)(30,38)(33,40)(35,36)(1,3,4,8)(2,6,5,7)(10,11)(15,17)(16,18)(19,24)(26,31)(27,35)(32,39)(34,36)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.