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