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