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