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