The Lewis structure of CS2 consists of a single carbon atom with one sulfur atom on each side. The bonds in the Lewis structure are either a double bond connecting the carbon atom to each sulfur atom, or one sulfur atom connecting with a triple bond and the other with a single bond.
Lewis structures for molecules are typically written through trial and error unless they are already known. The method for figuring out a Lewis structure requires that all of the valence electrons are accounted for, and all of the atoms in the structure end up with a full shell of valence electrons.
First, connect all of the atoms using the electronegativity of the elements to determine which atoms go where. Typically, if you have a carbon atom and several other atoms, the carbon atom will be in the center. In the case of CS2, the carbon atom is less electronegative and forms the center.
Next, determine how many electrons are present. In CS2, the sulfur atoms contribute six valence electrons each and the carbon atom contributes four for a total of sixteen. 24 electrons would be needed in order to provide all three atoms with a full valence shell of 8 electrons. This means that the CS2 molecule must have a total of 8 bonds connecting the three atoms.