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