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