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