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