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