Can you design your own circuit with a description of the parts needed, or would you prefer a schematic? A simple method is to use a bridge rectifier followed by a 470uF capacitor, feeding two strings of 12 LEDs (that's 24 total, not 25, I realise), with a 220-ohm resistor in series with each string. This will give around 14mA through the LEDs if the transformer output is actually close to 32VAC. You can stress out your LEDs if the transformer output voltage is actually higher than specified. You can put a constant current controller on each string (using a couple of transistors) to remove this possibility.