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