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