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