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