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