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