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