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