Could this be The Long Result by John Brunner? There seem to be a number of elements that match your description;

• Planet called Starhome - Check.
• Aliens called Relgans - Check (Regulans, actually)
• Book cover with rocket - Check
• Blue aliens - Check
• Legs that bend the wrong way - Check (described as "back-bent")
• Anti-hol - Check (described as "Anti-Alcohol")

This is The Long Result by John Brunner. There are a number of elements that match your description;

• Planet called Starhome - Check.
• Aliens called 'Relgans(?)' - Check (Regulans, actually)
• Book cover with rocket - Check
• Blue aliens - Check
• Legs that bend the wrong way - Check (described as "back-bent")
• Anti-hol - Check (described as "Anti-Alcohol")