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