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