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)(15,18)(16,17)(19,20)(22,25)(26,27) involution — undirected(2,4)(6,8)(10,12)(14,16)(18,19)(21,22,24,25)(23,27,28,26)(1,2)(3,4)(7,11)(10,12)(13,15,17,20)(14,18,16,19)(21,22,24,25)(23,26,28,27)(5,7,9,11)(6,10,8,12)(13,15)(14,19)(16,18)(17,20)(21,22)(23,27)(24,25)(26,28)(5,8,9,6)(7,10,11,12)(13,16,17,14)(15,19,20,18)(21,23,24,28)(22,26,25,27)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.