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