Are there any colorful, odorless gases?
There are plenty that are smelly and colourless, or are odourless and colourless but I would agree that there are none that are coloured and odourless. Surely it is just coincidental if any of these pairs occur because the chemistry involved in vision and smell are totally different. (Whatever the chemistry of smell is it does not involve photons!) If you were less restrictive in your conditions then most gases will be 'coloured' in the sense that they have electronic absorption in the near ultra-violet and also infra-red at longer wavelengths. Perhaps some insects would see gases such as N$_2$O or O$_3$ as coloured. Also if you were to allow vapours then many compounds can be considered if heated, for example azulene (an isomer of naphthalene) is blue and has a small but measurable vapour pressure if warmed slightly. I don't think I want to smell any, however. The ideal of filling ones nose and lungs with aromatic or dye vapours that then condense is not an attractive one!