Contact the programme coordinator in the subject on which you would be willing to give a talk. Guest speakers are a way of bringing academia and the world of work closer together. Real-world examples and experiences are invaluable, as is the opportunity to ask questions of someone who is working out in the field.
You have invaluable experience for our students and we would love to hear about it. You could give a guest lecture at one of our careers fairs, or give a talk to students on a programme or at a celebratory event.