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