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