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