This is the nucleotide dAMP, or deoxy-adenosine-5'-monophosphate. The phosphorus atom in the phosphate group is purple or pink, the sugar is a 5-membered ring with a red or orange oxygen atom in the ring, and the base, adenine, is a heterocyclic molecule, whose nitrogen atoms are blue.
There are four such nucleotides in DNA. The others are dCMP, dGMP, and dTMP.