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