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