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