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