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)(21,22)(23,27)(24,26)(25,28) involution — undirected(5,6,9,12)(7,8,11,10)(13,14)(15,20)(16,19)(17,18)(21,23,26,25)(22,27,24,28)(5,7)(6,10)(8,12)(9,11)(13,15,17,16)(14,19,18,20)(21,24,26,22)(23,27,25,28)(1,2)(3,4)(5,7)(6,8)(9,11)(10,12)(13,14)(15,19)(16,20)(17,18)(21,23,26,25)(22,28,24,27)(5,8)(6,11)(7,12)(9,10)(13,16,17,15)(14,19,18,20)(21,25,26,23)(22,27,24,28)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.