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