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