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