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