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