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