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