Well, yes, plain green can be boring, but variegated green is a bit more interesting, so a Spider plant (Chlorophytum comosum) will be fine. Better still, get one of those and a plain green plant with large leaves (Cast Iron plant maybe) and arrange them next to each other - the contrast will be interesting.

Bromeliads (Guzmania lingulata for instance) are worth a look, not because they're not green,but because they produce colourful flowers - the only drawback being that getting them to flower again is tricky, so usually they're temporary visitors. Saintpaulia, or African violet is often in flower most of the year,so although they're essentially green, they do at least produce decent flowers. This link here https://savvygardening.com/pet-friendly-house-plants/, whilst not showing many of the Latin or botanical names, does at least provide images of most of the plants mentioned. The 'Swedish Ivy' mentioned near the bottom you likely won't be interested in - its green and small, and is Plectranthus verticillatus, in case you want to check what it looks like. Equally, 'Cast Iron plant' is mentioned - that is Aspidistra elatior, yet another plain green plant.

One thing to remember though; suit the conditions you have indoors to the conditions the plant requires before buying. Finally, if your cats do not have free access to the outdoors, then providing them with some cat grass https://m.petmd.com/cat/care/evr_ct_how-to-grow-cat-grass should deter their plant chewing habits - they really do need to eat grass periodically, and if they can't, they will chew on houseplants instead.