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