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