The Yang Mills fermion wave function

Let’s say we are working with SU(3). So we will have 3 dirac particles, or a 12 component spinor. My questions are: when we write an expression for the fermion-gluon vertex, does an external line represent a state of 3 particles or 1? When we write the free fermion propagartors we should have a (iota/ gamma.p - m) matrix, will it be a 4x4 matrix? We should also get a Kronecker delta, it should represent only one fermion amplitude right?