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