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