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