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