The charity will launch an integrated campaign next week called Think Differently About Autism, designed to improve understanding of the condition.
Focus group research costing £25,000 revealed that the society was seen as distant.
"The results from our research showed that we had quite a confused approach to our communications and were sending out different messages to different groups of people," said Benet Middleton, director of communications and public affairs at the society. "Some people didn't even realise we were a charity."
The logo has changed from blue and green to pink and purple, which Middleton said were more welcoming colours. The society also has a new strapline: "Your autism charity".
"It's not simply about changing the colour," said Middleton.