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