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