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