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