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