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