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