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