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