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