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