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