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