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