Elephants are one of the smartest animals on the planet. They have complex social roles and do things we rarely associate with animals, like visiting the graves of their dead. Because they are so large and strong, but also so gentle and intelligent, drawing and painting elephants allows the artist to evoke emotions that would seem out of place with many other animals.
Elephants are perfectly suited to pencil drawings because of their grey color and also because of the details on their skin, like their mottled trunks and the wrinkles around their eyes and the texture of the skin on their ears. Super-realistic, almost photograph-like drawings of elephants seem to capture them well, but drawing them on the savanna, with a dramatic sunset or calming landscape behind them in pastels would also work.
Of course, while most elephants are gentle and calm, there is almost nothing in nature as terrifying and awesome as an attacking bull elephant. If you want to draw one of those, you could use splatters of pen and ink or the ragged strokes of a charcoal to depict the feeling of the world ripping apart under the elephant's attack.