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