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