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