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