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