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