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