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