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