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