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