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