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