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