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