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)(15,24)(16,18)(17,20)(19,23)(21,25)(22,26)(27,28) involution — undirected(5,6,9,10)(7,11,8,12)(13,15,19,25)(14,20,23,27)(16,24,22,21)(17,18,28,26)(5,7,9,8)(6,11,10,12)(13,16,26,23,19,22,18,14)(15,24,28,20,25,21,17,27)(2,4)(5,8,9,7)(6,11,10,12)(13,17,18,25,19,28,26,15)(14,21,22,20,23,24,16,27)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.