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