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