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