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