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