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