Yes and no ^^ In principle, you could use it to supply a graphics card with power, but only if this cable is compatible with the power supply unit. Each power supply manufacturer may use different pin assignments in the production of their power supplies and cables. Seasonic power supply cables, for example, would most likely not work with a Corsair power supply.
Power supply cables from the same manufacturer as the power supply itself usually fit. However, only the cables supplied with the power supply unit or those explicitly specified by the manufacturer as compatible with this power supply unit (or a series of power supply units) will work.