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