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