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