Mention a hobby if it is unique or unusual, but projects a positive image of you. Especially mention a hobby that somehow relates to engineering. Use a good quality, heavy, off-white or white paper. Light-weight paper will cheapen the effect of your resume. If you use colored paper, make sure that it photocopies well.
Color is acceptable when done tastefully and within limits.
Your are probably better off staying with black and white. If you decide to use colored items, make sure that they photocopy well. Do not overcrowd the resume. Avoid excessive use of bullets, underlining, italicizing, or bolding. Entry-level resumes should almost never exceed one page.