One vertex per element, one color per generator, with an edge from x to x·s.
(1,2) involution — undirected(3,4)(5,8)(6,7)(9,10)(11,12)(13,16,20,23)(14,17)(15,18)(19,22,25,26)(21,24)(11,13)(12,16,18,23)(14,19)(15,20)(17,22,24,26)(21,25)(4,7)(8,10)(11,14)(12,17)(13,19)(15,21)(16,22)(18,24)(20,25)(23,26) involution — undirected(3,5,6,9)(4,8,7,10)(14,21)(17,24)(19,25)(22,26)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.