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