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