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