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