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