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