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