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