The use of graphics in tenders is a fairly common occurrence, with bidders applying focus on the presentation of their bids. The presentation of your tender can have a real impact, and as an obvious visual aid, it can also provide the reader an indication of your professionalism.
If do you choose to use graphics in your presentation of your tender, remember that there is a fine balance to achieve your goal. Think about what message you are wanting to give the reader, and look to keep the graphics as simple as possible. Also, before you you make a final decision, be as objective as you can, and try to look at the graphics from the position of the reader. This is always a difficult task - to be self critical - so maybe ask a friend or colleague for their opinion.