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