I am afraid that the circuit is incomplete.

The way you have shown it will not deliver what you want.

For digitally selecting voltages, you permanently connect the resistor between the Output and Adj. pin ( 240 Ohm in your case )and use the relay changeover contacts to select the resistor connected to the Adj. pin ( 470 Ohms ). And here also just dont wire one resistor each from NC and NO contacts - this can lead to a momentary loss of control when the relay changes over. Wire one resistor permanently and use the relay contact (NO) to bring in the second resistor parallely across the permanent fellow.

Refer to the LM317 data sheet from National and they have an application note for digitally selected outputs using transistors - OK in your case it is relay - but the idea will be clear.

Raghu