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