Buses, trains and trams from across the Perth-based transport group’s empire are featured in A Very Special Family Party, which is set at Mr Souter’s house in the city.
They include a Scottish Citylink and a Megabus Gold coach, with other characters including Hamish the helicopter - although the company doesn’t own one.
The cover of the 16-page book is dominated by Bobby the Bus, one of the main characters, who is accompanied by Molly the Megabus, and others from Oxford and the United States.
The story tells of this “family” travelling to Perth for Mr Souter’s party, and includes a surprise present and a rescue.
The book was itself created as a surprise for Mr Souter’s birthday on Monday.
Stagecoach said at least £1.50 of the £4 price would be donated to the trust to boost children’s literacy.
The trust works in areas of the UK where up to 40 per cent of people have literacy problems.
Author Lindsay Reid, who is Stagecoach’s Perth-based senior group communications manager, said: “I just wanted to come up with something that was light-hearted and fun, with strong illustrations, that children will enjoy. Adults seem to be enjoying it so far too.
“Many children are fascinated by public transport, and our bus companies across Scotland visit schools regularly as part of their transport projects, so we are pleased to have been able to bring our buses, trains and trams to life in this way.”
Other characters include Stanley Supertram from Sheffield, and from South West Trains and East Midlands Trains in England.
Mr Souter said: “The book is definitely one of the more unusual birthday presents I’ve received.
“It’s a great idea, which we hope children will enjoy, and it reminds us there’s a fun side to transport too.”
Lorna Taylor, corporate partnerships manager at the trust, said: “One person in six in the UK lives with poor literacy and this holds them back at every stage of their life.
“Our interest is in supporting some of the UK’s poorest children and families to improve their literacy skills, and funds raised by Stagecoach Group’s children’s book will help us to achieve this vital goal.”