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