Question regarding the colour of Benzoic acid and Benzyl alchohol
none of the components you mentioned (Benozic acid, Benzyl alcohol, sodium benzoate) has a yellow colour.
The colour in organic compouns is closely tied to ther delocalized sytems of pi-electrons and depends on the gap between the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO).
When the energy of this gap corresponds to a wavelength that is visible, the compound absorbs this wavelength and the colour of the compound is the complementary colour.
A good example are condensated aromats. For benzene or naphthalene the gap between HOMO and LUMO is too big therefore, the corresponding wavelength is in the area of UV light.
For anthracene, the absorbed wavelenght is violett and therefore the colour of the compound is yellow.
Back to your question. Because the reaction happends under strong basic conditions, high temperature and with many aromatic compounds, I think sidereactions will occure where multiple aromats condensate together and therefore the solution turns yellow to orange.