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