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