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