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