TOKYO, Oct 7 - Japan's diffusion index of leading economic indicators for August stood at a preliminary 55.6 on a scale of 100, down from a revised 80.0 a month earlier, the government said on Tuesday. The leading index, compiled using data such as the number of new job offers, consumer sentiment and Tokyo share prices, is taken to signal economic conditions for the next few months. It was slightly above the critical 50 level, which marks the difference between expansion and contraction in the coming months, for the third straight month. The coincident index, which indicates current economic conditions, was also at a preliminary 55.6 in August, down from a revised 80.0 in July, the Cabinet Office said.//