The tone of this well-known poem by Leopold Sedar Senghor is solemn. This is displayed through the choice of certain words and expressions, such as "I greet you in silence."

Senghor was a Senegalese statesman and also the president of this state from 1960 to 1980. The tone of the poem, in accordance with Senghor's strong political spirit, is exhortative. He does not ask the masks, which represent his ancestors, to listen to him; rather, he commands them to listen. This is a sign of a strong and determined personality, as ancestors are usually addressed with an almost reverential fear in many cultures.

Masks of maskless faces, free from dimples and wrinkles.
You have composed this image, this my face that bends
over the altar of white paper.
In the name of your image, listen to me!

Readers feel hopeful, inspired and empowered at the same time. Africa is shown as a source of beauty, life, and positivity, whereas Europe, the "mother," is flailing. Africa is shown as the force that can breathe life back into European civilization, even though "they" (the Europeans) do not recognize this and call the Africans "cotton heads, coffee men and oily men." Despite this, the Africans have the rhythm and life which is dying in Europe, and they can bring joy, laughter, and hope back to Europe. The mood of the poem is therefore positive, inspiring, hopeful, and empowering.

Tone is an author’s attitude toward a subject.  Mood, on the other hand, is the emotional environment created by the words.  I would say that this poem is hopeful, pleading and celebratory.  Consider the tone with words such as “through whom the spirit breathes” (line 3) and “You purify the air of eternity, here where I breathe the air of my fathers” (line 8).  These are hopeful to me.

There are also some pleading lines such as “In the name of your image, listen to me!” (line 12) and “Now turn your immobile eyes towards your children who/have been called/And who sacrifice their lives like the poor man his last garment” (lines 17-19).

Finally, the tone is also celebratory:

For who else would teach rhythm to the world that has
died of machines and cannons?
For who else should ejaculate the cry of joy, that arouses the dead and the wise in a new dawn?
Say, who else could return the memory of life to men with a torn hope? (lines 22-26)

This seems to be the speaker suggesting a rebirth of Africa, and pride in Africa.

So when the reader reads this poem, he or she might feel a mood of hope or celebration.  The speaker’s words create this affect due to their tone.