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