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