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)(15,18)(16,24)(17,21)(19,23)(20,25)(22,27)(26,28) involution — undirected(1,2)(3,4)(6,9)(7,11)(13,15,18,14)(16,22,26,20)(17,21,19,23)(24,25,28,27)(2,4)(5,7,8,11)(6,10,9,12)(13,16)(14,20)(15,22)(17,25)(18,26)(19,27)(21,28)(23,24)(6,9)(10,12)(14,15)(20,22)(21,23)(24,28) involution — undirected(2,4)(13,17,18,19)(14,21,15,23)(16,25,26,27)(20,28,22,24)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.