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