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